Product and method to manufacture multi-layered, multi-material composite sandwich structure with hyper elasticity rubber like core made by fusion deposition modeling

ABSTRACT

A method for manufacturing a hyper-elastic three-dimensional (3D) sandwich panel is disclosed, the method comprising printing a plurality of layers, the plurality of layers comprising a central composite core and upper and lower sandwich face layers; and regulating a temperature of each printed layer to match melting point temperature of a consecutive layer being subsequently printed on top of a previously printed layer, wherein the plurality of layers are printed one layer at a time. The multi-layered and multi-material hyper-elastic three-dimensional (3D) sandwich panel is a central composite rubber core stacked between upper and lower sandwich face layers made of reinforced glass-fiber, wherein the central composite rubber core further comprises a core lower face layer, a central core layer and a core upper face layer.

FIELD OF THE INVENTION

The present invention relates to a hyper elastic sandwich structure manufactured using Fused deposition modeling (FDM), and more particularly a method for manufacturing a multi-layered multi-material composite sandwich structure.

BACKGROUND OF THE INVENTION

Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

Fused deposition modeling (FDM) is one of the most widely used additive manufacturing processes for fabricating prototypes and functional parts in common engineering plastics. The process is based on the extrusion of heated feedstock plastic filaments through a nozzle tip to deposit layers onto a platform to build parts layer by layer directly from a digital model of the part. The simplicity, reliability, and affordability of the FDM process have resulted in the additive manufacturing technology to be widely recognized and adopted by industry, academia, and consumers. The FDM process has also been widely used by research and development sectors to improve traditional processes, to develop new materials, and apply FDM systems in a wide range of engineering applications.

Polycaprolactone (PCL), a medical-grade thermoplastic polyurethane, is generally used in FDM for scaffold production. PCL is preferred due to its high decomposition temperature and low glass transition. Therefore, the application of this method to biodegradable polymers except PCL is limited. Besides, incorporation of cells or biological factors in the overall procedure is avoided owing to the high operational temperatures.

One of the biggest challenges of 3D printing is printing with flexible materials like rubber. Rubber is an organic material whose properties cannot be influenced by external factors. The fact that rubber undergoes vulcanization to improve its elasticity and strength implies that it can never again re-exist in a fluid state. Initially, printing flexible filaments caused designers a lot of trouble, considering that the filaments were too soft, and whenever passed through a 3D printer, printing did not occur as expected. Most of the extruders used had a pushing string effect. Whenever a filament with no rigidity was pushed towards the nozzle, the filament bent or twisted because it was too soft. Flexible, rubber-like filaments include all such filaments coming from various manufacturers. The formulas for these filaments vary from one manufacturer to another, and this results in printing stacked layers of different materials to be a challenging task.

Apart from flexible filaments, flexible resin is also traditionally used to produce rubber-like prints (for developing or prototyping highly precise flexible parts). When printed, flexible resin feels just like rubber and normally compresses and is capable of bouncing back to original form. However, a main drawback is that resins are normally designed for specific printers and there is no compatibility of rubber-like material (such as TPU95A) with polymeric materials owing to adhesion problems, as shown in the below table:

Tough TPU PLA PLA ABS Nylon CPE CPE+ PC 95A PP PVA Breakaway PLA ✓ E x x x x x x x ✓ ✓ Tough ✓ x x x x x x x ✓ ✓ PLA ABS ✓ x x x x E x E ✓ Nylon E x x x E x ✓ ✓ CPE ✓ x x x x ✓ ✓ CPE+ E x x x E ✓ PC E E x x E TPU 95A E x E E PP E x x PVA x x Breakaway x ✓—Officially supported E—Experimental x—Not supported

Accordingly, there exists a need for a solution for the above explained issues, and for a sandwich panel that overcomes the drawbacks faced by traditional products and a method of manufacturing the same.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to develop a multi-layered, multi-material composite sandwich structure which overcomes drawbacks faced by traditional products.

In an aspect of the invention, the present invention relates to a method for manufacturing a hyper-elastic three-dimensional (3D) sandwich panel, the method comprising the steps of printing a plurality of layers, the plurality of layers comprising a central composite core and upper and lower sandwich face layers; and regulating a temperature of each printed layer to match melting point temperature of a consecutive layer being subsequently printed on top of a previously printed layer, wherein the plurality of layers are printed one layer at a time.

In an embodiment of the present invention, 3D printing fusion deposition modelling (FDM) technology is used for manufacturing the hyper-elastic 3D sandwich panel.

In another embodiment of the present invention, the central composite core is a rubber core stacked between the upper and lower sandwich face layers made of reinforced glass-fiber.

In another embodiment of the present invention, the central composite core further comprises a core lower face layer, a central core layer and a core upper face layer.

In another embodiment of the present invention, the method further comprises spraying a bonding agent over the lower sandwich face layer prior to printing the core lower face layer for achieving additional adhesion strength between various materials being used in the plurality of layers.

In another embodiment of the present invention, the hyper-elastic 3D sandwich panel comprises multiple core layers stacked in between upper and lower sandwich face layers.

In another embodiment of the present invention, a non-contact digital laser infrared thermometer temperature gun is used for measuring temperature of the central composite core, and for ensuring that the central composite core has attained a desired temperature prior to proceeding with printing of the consecutive layer.

In another embodiment of the present invention, a thermal camera or IR thermometer with laser pointers is used for monitoring and thereby regulating temperature of each layer being printed and for determining as to when printing should stop or resume.

In another embodiment, a control screen is used to set a temperature of a material being used for printing prior to commencement of the printing, and is connected to a thermal camera controller and a 3D printer controller.

In another embodiment of the present invention, two FDM extruder nozzles are used for 3D printing the plurality of layers, one layer at a time.

In another embodiment of the present invention, the method further comprises the steps of:

heating a printing bed to 30% of the melting point of a material used in the lower sandwich face layer;

-   -   heating a first FDM nozzle and printing the lower sandwich face         layer with a linear infill type;     -   allowing the first FDM nozzle to cool down subsequent to         printing the lower sandwich face layer and heating a second FDM         nozzle;     -   allowing the lower sandwich face layer to cool down until         temperature approaches 50% of the melting point of a material         used in the core lower face layer;     -   printing the core lower face layer over the lower sandwich face         layer using the second FDM nozzle;     -   printing the composite central core over the core lower face         layer using the second FDM nozzle;     -   printing the core upper face layer over the core lower face         layer using the second FDM nozzle with a linear infill type;     -   allowing the second FDM nozzle to cool down subsequent to         printing the core upper face layer and heating the first FDM         nozzle;     -   allowing the core upper face layer to cool down until         temperature approaches 50% of the melting point of a material         used in the upper sandwich face layer;     -   printing the upper sandwich face layer over the core upper face         layer using the first FDM nozzle; and     -   allowing the first FDM nozzle to cool down subsequent to         printing the upper sandwich face layer.

In another embodiment of the present invention, the second FDM nozzle is heated to 50% of the melting point of the material used in the core lower face layer.

In yet a further aspect of the invention is disclosed, a multi-layered and multi-material hyper-elastic three-dimensional (3D) sandwich panel comprising a central composite rubber core stacked between upper and lower sandwich face layers made of reinforced glass-fiber.

In an embodiment of the present invention, the central composite rubber core further comprises a core lower face layer, a central core layer and a core upper face layer.

In another embodiment of the present invention, the core lower face layer, the central core layer and the core upper face layer are made of rubber or a flexible rubber-like material, to ensure hyper elasticity properties and an ability to maintain shape when no load is placed on the 3D sandwich panel.

In another embodiment of the present invention, the lower and upper sandwich face layers are made of reinforced materials such as fiber glass or carbon fiber reinforced polymers.

In another embodiment of the present invention, a transition layer is present in between the upper sandwich face layer and the central composite rubber core for enhancing adhesion characteristics between the upper sandwich face layer and the central composite rubber core.

In another embodiment of the present invention, an interfacial surface between the transition layer and a surface of the core upper face layer comprises a low infill density of 10% to 50%.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter that is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other aspects, features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 illustrates a single core composite hyper elastic sandwich panel in accordance with the present invention.

FIG. 2 depicts a hyper elastic rubber-like composite core sandwich panel with 2 core layers in accordance with the present invention.

FIG. 3 depicts a hyper elastic rubber-like composite core sandwich panel with 3 core layers in accordance with the present invention.

FIG. 4 shows positioning of a transition layer in accordance with the present invention.

FIG. 5 shows various infill types and layer densities of the multi-layered, multi-material composite sandwich structure in accordance with the present invention.

FIG. 6 is a flow chart depicting the manufacturing process of a multi-layered and multi-material hyper elastic sandwich panel using 3D printing technology fusion deposition modelling (FDM), in accordance with the present invention.

FIG. 7 depicts the thermal camera or IR thermometer with laser pointers in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The aspects of a multi-layered, multi-material composite sandwich structure according to the present invention will be described in conjunction with FIGS. 1-7. In the Detailed Description, reference is made to the accompanying figures, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

Fusion Deposition Modelling (FDM) is a production method used for fabrication, production applications, and mechanical system modeling. The technique produces a tissue scaffold by a melt extrusion method which makes use of a layer-by-layer thermoplastic polymer. FDM utilizes a moving nozzle to extrude a fiber of polymeric material (x- and y-axis control) from which a physical model is built layer-by-layer. FDM technique has several advantages compared to other 3D printing technologies, such as absence of any unbound loose powder and elimination of any kind of solvent removal process.

The proposed invention aims at manufacturing a multi-layered and multi-material hyper elastic sandwich panel using 3D printing technology fusion deposition modelling (FDM) also known as fused filament fabrication. FDM 3D printing works both horizontally and vertically, using an extrusion nozzle which moves over a platform. The process involves the use of thermoplastic material that reaches melting point and is then forced out for creating a 3D object layer by layer. The sandwich panel in accordance with the present invention, includes a rubber-like core which provides a required elasticity and is stacked between two layers—upper and lower layers made of glass-fiber reinforced nylon. The present invention deals with a product and method for manufacturing the product. Owing to differences in melting point and adhesion characteristics, traditionally, 3D FDM printing was unable to effectively perform using rubber-like material stacked on polymeric material. Accordingly, multiple tests were conducted to identify a better and more successful method for the same, resulting in the hyper elastic sandwich panel made with a rubber core and glass-fiber reinforced upper and lower layers.

This unique combination provides the product with hyper elasticity, and the ability to maintain shape even when no load is placed. In another embodiment of the present invention, a method of the manufacturing is proposed for building multi-layered sandwich panels with numerous rubber-like cores that have superior properties (considering the combination of super flexibility with upper and lower faces).

Various properties of the hyper elastic sandwich structure in accordance with the present invention include that the central composite core includes three main components namely, the core lower face layer 110, the central core 108 and the core upper face layer 106. All these three layers are made of rubber or any other high flexible rubber-like material. Further, the lower and upper sandwich face layers are made of reinforced material such as fiber glass or carbon fiber reinforced polymers like nylon or polylactic acid (PLA) reinforced with randomized particles or unidirectional glass or carbon fiber. Properties such as length and thickness of the sandwich layers depend on the required overall stiffness. In another embodiment of the present invention, infill properties pertaining to the rubber-like central core 108 depend on the hyper elasticity property of the core. However, the infill type must always be linear style for excellent adhesion properties between interfacial layers when transitioning between the core lower face layer 110 to central core 108 and then from the central core 108 to the core upper face layer 106.

In another embodiment, a non-contact digital laser infrared thermometer temperature gun is used for measuring temperature of the rubber-like central core 108, to ensure that the central core has attained the desired temperature prior to proceeding with printing of the next sandwich layer.

FIG. 1 illustrates a single core composite hyper elastic sandwich panel in accordance with the present invention. In FDM, an extruder nozzle deposits material along the footpath, fusing it to previous layers in order to build a three-dimensional body, thus being called Fused Deposition Modeling. The manufacturing process commences by initially heating the printing bed 114 up to 30% of the melting point of the material used in the sandwich lower face layer 111 (with temperature T2). This is followed by heating the active FDM Nozzle 1 103 to temperature T_(N1) and printing over the bed 114 (with temperature T1) with a linear infill type. Infill is a repetitive structure used to fill up space inside an otherwise empty 3D print. For the majority of prints, infill is hidden from view (however possesses numerous patterns, designs and orientations). The infill also enables printers to print flat horizontal edges over empty space reliably and efficiently without which 3D prints will fail to have sufficient structure or stability, and will be fragile. Prior to the completion of printing the sandwich lower face 111, FDM Nozzle 2 104 with temperature T_(N2) is heated to 50% of the melting point of the material used in the core lower face layer 110 (with temperature T3).

Once the sandwich lower face 111 is printed, FDM Nozzle 1 103 moves to a stand by position or condition and gradually cools down with the help of a cooling fan. The sandwich lower face 111 (at temperature T2) is also left to cool down by natural convection or a fan until temperature T2 approaches 50% of the core lower face layer 110 melting temperature T3. Temperature may be measured manually or by using a thermal cameral 112 integrated with the 3D printer to control the overall cooling process and thereby when the printing process may resume. In an embodiment of the present invention, a bonding agent is sprayed over the sandwich lower face 111 prior to printing the core lower face layer 110—for additional adhesion strength between the materials being used. Hence, FDM Nozzle 2 104 continues to heat up until approaching core lower face layer 110 melting temperature T3, and starts printing over the sandwich lower face 111 with a linear infill style.

Subsequent to completion of printing the core lower face layer 110, FDM Nozzle 2 104 proceeds to print the rubber-like composite central core 108 with temperature T4, which is equal to T3 and an infill core. The infill may be, but not limited to any one of linear, honeycomb, triangular or concentric, depending on individual and respective design requirements. Once the central core 108 is printed, FDM Nozzle 2 104 proceeds to print core upper face layer 106 with a linear infill at temperature T3 which is equal to T4. Prior to the completion of printing the core upper face layer 106, FDM Nozzle 1 103 with temperature T_(N1) is heated to 50% of the melting point of the material to be used in the sandwich upper face layer 110 (with temperature T2). Once the core upper face layer 106 is printed, FDM Nozzle 2 104 moves to a stand by position or condition and gradually cools down with the help of a cooling fan. The core upper face layer 106 (at temperature T3) is also left to cool down by natural convection or a fan until temperature T2 approaches 50% of the sandwich upper face 105 melting temperature T2. Temperature may be measured manually or by using a thermal camera 112 integrated with the 3D printer to control the overall cooling process and thereby when the printing process may resume. In an embodiment of the present invention, a bonding agent is sprayed over the various face layers for additional adhesion strength between the materials being used.

FDM Nozzle 1 103 proceeds to print the sandwich upper face 105. Subsequent to printing of the sandwich upper face 105, FDM Nozzle 1 103 stops printing moves to a stand by position or condition and gradually cools down with the help of a cooling fan. The method in accordance with the present invention is also used to manufacture hyper elastic rubber-like composite core sandwich panels with multiple cores (2 or more core layers) as shown in FIGS. 2 and 3, comprising a single layer or a core mid-face layer 109 between the first and second core layers 108 a and 108 b, to provide an interfacial zone between the rubber-like core layers and the glass-fiber reinforced upper and lower sandwich faces 105 and 111. FIG. 3 depicts hyper elastic rubber-like composite core sandwich panels with 3 core layers 108 a-108 c, and two core mid-face layers 109 a and 109 b.

In an embodiment of the present invention, and as shown in FIG. 4, a transition layer 102 is present in between the sandwich upper face 105 and the central core 108. Interfacial surface between the transition layer 102 and surface of the core upper face layer 106 includes a low infill density of 10% to 50%. Two different combinations of infill structures are used to offer more contact surface to secure adhesion. Printing process of the sandwich upper face 105 cannot be done without following the temperature requirements of the manufacturing process described above. Prior to printing the sandwich upper face 105, a chemical agent is sprayed over the upper surface of the transition layer 102 (for increased adhesion strength). The same conditions are applied for the interfacial surface between the transition layer 102 and the surface of the upper core layer 106. The proposed method of manufacturing the multi-layered, multi-material composite sandwich structure includes preparing or building the various layers individually for any kind of material combination. Special consideration in the proposed method is given to ensure proper adhesion characteristics between the various layers being printed.

The proposed invention uses a plurality of traditional nozzles for printing and stacking the various independent layers of the sandwich structure. Further, the proposed method comprises a temperature control system for monitoring and controlling overall temperature of the printing process, particularly measuring temperature of the last printed layer of a specific material, in order to prepare the last printed layer for printing the next different material to be stacked over the previous layer, in order to ensure proper adhesion. Also, there is a transition layer 102 present in the proposed structure, which further enhances proper adhesion characteristics between the polymeric material and the rubber-like material through monitoring and controlling temperature of the interfacial surface between the transition layer 102 and the rubber-like core layer 108. Temperature control is done manually or by using a closed-loop thermal camera 112.

The proposed product (multi-layered, multi-material composite sandwich structure) using polymeric material for the sandwich faces and rubber material for the core is tested for various properties, wherein the product manufactured by FDM process displayed hyper-elastic properties subsequent to the test, as the product was shown to recover its original shape after removing an applied load. The primary objectives of this product include providing ordinary users a cheap and practical method for manufacturing a composite sandwich with a rubber core using FDM 3D printing technology. Further, the end-product which is a hyper flexible sandwich panel with a central rubber core and covered with composite layers—has numerous industrial applications in the construction, automobile, aerospace and marine fields.

FIG. 5 shows various infill types and layer densities of the multi-layered, multi-material composite sandwich structure in accordance with the present invention. The upper surface of the sandwich upper face 105 has 100% density and line infill type, and the lower surface of the sandwich upper face 105 has 10-50% density and consists of any infill type. The transition layer 102 also has 10-50% density and consists of grid or triangular infill type. Further, the upper surface of the central core 108 has a smooth finish with 100% density (same material as the rubber core) with line infill type. The sandwich rubber core 108 has 10-50% density and consists of any infill type.

FIG. 6 is a detailed flow chart depicting the steps in the manufacturing process of a multi-layered and multi-material hyper elastic sandwich panel using 3D printing technology fusion deposition modelling (FDM), in accordance with the present invention. As a first step, the printing bed 114 is heated up (to 30% of the melting point of the material used in the sandwich lower face layer 111). This is followed by heating active FDM Nozzle 1 103 (to temperature TN1) and printing over the printing bed 114 with a linear infill type. In the next step, FDM Nozzle 2 104 is heated up (to 50% of the melting point of the material used in the core lower face layer 110). Once the sandwich lower face 111 is printed, FDM Nozzle 1 103 moves to a stand by position or condition and gradually cools down with the help of a cooling fan. The sandwich lower face 111 (at temperature T2) is also left to cool down by natural convection or a fan until temperature T2 approaches 50% of the core lower face layer 110 melting temperature T3. FDM Nozzle 2 104 continues to heat up until approaching the desired core lower face layer 110 melting temperature, and starts printing over the sandwich lower face 111 with a linear infill style.

In the next step, subsequent to completion of printing the core lower face layer 110, FDM Nozzle 2 104 proceeds to print the rubber-like composite central core 108. Once the central core 108 is printed, FDM Nozzle 2 104 proceeds to print core upper face layer 106 with a linear infill. Prior to the completion of printing the core upper face layer 106, FDM Nozzle 1 103 is heated (to 50% of the melting point of the material to be used in the sandwich upper face layer 110). Once the core upper face layer 106 is printed, FDM Nozzle 2 104 moves to a stand by position or condition and gradually cools down with the help of a cooling fan. The core upper face layer 106 (at temperature T3) is also left to cool down by natural convection or a fan until temperature T2 approaches 50% of the sandwich upper face 105 melting temperature T2. In the next step, FDM Nozzle 1 103 proceeds to print the sandwich upper face 105. Subsequent to printing of the sandwich upper face 105, FDM Nozzle 1 103 stops printing moves to a stand by position or condition and gradually cools down with the help of a cooling fan.

The present system produces a multilayer sandwich instead of a composite material including a filler mixed with a polymer. FIG. 7 depicts the thermal camera or infrared (IR) thermometer with laser pointers 112 in accordance with the present invention, integrated with the 3D printer to control the overall cooling process of each layer and determine as to when the printing should stop or resume. Also shown in FIG. 7 is a 3D printer frame 113 and a control screen 107. The control screen 107 is used to set a temperature of the used material used in the 3D printing process prior to commencement of any printing, and is connected to a thermal camera controller 115 and a 3D printer controller 116. The thermal camera or IR thermometer sensor 112 measures the top surface temperature of a 3D printed layer, and triggers sending of an order (a signal) to the 3D printer controller 116 in case the top surface requires cooling or heating for matching conditions for achieving high interfacial adhesion strength while printing, and will be ready to start printing the next layer. This combats the traditional problem faced pertaining to compatibility of adhesion characteristics—when 3D printing different materials. So, considering the scenario wherein temperature fails to match at the time of starting to print a new layer, a signal is sent to both the thermal camera controller 115 and the 3D printer controller 116 for the 3D printer to stop printing a new consecutive layer. When the desired temperature of the top surface is reached and measured by the real-time thermal camera 112, the printer resumes printing the consecutive layer.

The following steps elaborate the role of the control screen 107 in the printing process, in accordance with the present invention. First, the 3D printer is switched on and a sliced CAD file (of the multi-layered sandwich panel) is uploaded to the 3D printer. The control screen 107 is used to then set the temperature of each material to be used and subsequently, 3D printing commences. On completing the top surface of the first layer, the 3D printer controller 116 sends an order to the thermal camera 112 to measure the top surface of the first layer, if the temperature matches the conditions, the thermal camera controller 115 sends an order to the 3D printer controller 116 to continue printing the second layer. If the temperature does not match the conditions, the thermal camera controller 115 orders the 3D printer controller 116 to pause the 3D printing process, and to regulate the temperature of the top surface layer (by cooling or heating using an air blower which is attached with the 3D printer). The 3D printer is also equipped with a heater which is switched off in case the layer needs cooling only. When the temperature of the top surface matches the condition desired through the measured temperature by the thermal camera 112, the thermal camera controller 115 stops the cooling or heating process and triggers an order to the 3D printer controller 116 to continue the 3D printing process of the next layer. This process is continued for other layers until the last layer of the sandwich panel is printed.

Many changes, modifications, variations and other uses and applications of the subject invention will become apparent to those skilled in the art after considering this specification and the accompanying drawings, which disclose the preferred embodiments thereof. All such changes, modifications, variations and other uses and applications, which do not depart from the spirit and scope of the invention, are deemed to be covered by the invention, which is to be limited only by the claims which follow. 

The invention claimed is:
 1. A method for manufacturing a hyper-elastic three-dimensional (3D) sandwich panel, the method comprising the steps of: printing a plurality of layers, the plurality of layers comprising a central composite core and upper and lower sandwich face layers, wherein the central composite core comprises a core lower face layer, a central core layer and a core upper face layer; heating a printing bed to 30% of a melting point of a material used in the lower sandwich face layer; allowing a first fusion deposition modelling (FDM) nozzle to cool down subsequent to printing the lower sandwich face layer and heating a second FDM nozzle for printing the core lower face layer, the central core layer and the core upper face layer; allowing the second FDM nozzle to cool down subsequent to printing the core lower face layer, the central core layer and the core upper face layer and heating the first FDM nozzle for printing the upper sandwich face layer over the core upper face layer; and regulating a temperature of each printed layer to match melting point temperature of a consecutive layer being subsequently printed on top of a previously printed layer, wherein the plurality of layers are printed one layer at a time.
 2. The method of claim 1, wherein 3D printing fusion deposition modelling (FDM) technology is used for manufacturing the hyper-elastic 3D sandwich panel.
 3. The method of claim 1, wherein the central composite core is a rubber core stacked between the upper and lower sandwich face layers made of reinforced glass-fiber.
 4. The method of claim 1, further comprises spraying a bonding agent over the lower sandwich face layer prior to printing the core lower face layer for achieving additional adhesion strength between various materials being used in the plurality of layers.
 5. The method of claim 1, wherein the hyper-elastic 3D sandwich panel comprises multiple core layers stacked in between upper and lower sandwich face layers.
 6. The method of claim 1, wherein a non-contact digital laser infrared thermometer temperature gun is used for measuring temperature of the central composite core, and for ensuring that the central composite core has attained a desired temperature prior to proceeding with printing of the consecutive layer.
 7. The method of claim 1, wherein a thermal camera or IR thermometer with laser pointers is used for monitoring and thereby regulating temperature of each layer being printed and for determining as to when printing should stop or resume.
 8. The method of claim 1, wherein a control screen is used to set a temperature of a material being used for printing prior to commencement of the printing, and is connected to a thermal camera controller and a 3D printer controller.
 9. The method of claim 1, wherein two FDM extruder nozzles are used for 3D printing the plurality of layers, one layer at a time.
 10. The method of claim 1, further comprising the steps of: heating a first FDM nozzle and printing the lower sandwich face layer with a linear infill type; allowing the lower sandwich face layer to cool down until temperature approaches 50% of the melting point of a material used in the core lower face layer; printing the core lower face layer over the lower sandwich face layer using the second FDM nozzle; printing the composite central core over the core lower face layer using the second FDM nozzle; printing the core upper face layer over the core lower face layer using the second FDM nozzle with a linear infill type; and allowing the core upper face layer to cool down until temperature approaches 50% of the melting point of a material used in the upper sandwich face layer.
 11. The method of claim 10, wherein the second FDM nozzle is heated to 50% of the melting point of the material used in the core lower face layer.
 12. The method of claim 10, further comprising the steps of: printing the upper sandwich face layer over the core upper face layer using the first FDM nozzle; and allowing the first FDM nozzle to cool down subsequent to printing the upper sandwich face layer.
 13. The method of claim 2, wherein FDM technology uses thermoplastic polymer material for 3D printing.
 14. The method of claim 1, wherein a transition layer is printed between the upper sandwich face layer and the central composite core for enhancing adhesion characteristics between each of the plurality of layers.
 15. The method of claim 14, wherein temperature of an interfacial surface between the transition layer and a subsequent layer being printed is monitored and regulated, for ensuring proper adhesion between each of the plurality of layers being printed. 